11. Consider Traffic Control for Laredo Dr and Market Blvd at West 78th St. C I TY 0 F /1
CHANHASSEN
690 COULTER DRIVE • P.O. BOX 147 • CHANHASSEN, MINNESOTA 55317
' (612) 937-1900 • FAX (612) 937-5739
Mori Vf Mrnin}Straf:,F
MEMORANDUM Ent
TO: Gary Warren , City Engineer Edified
FROM: Charles Folch, Assistant City Engineer
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DATE: September 5 , 1990
DQtt J rr
' SUBJ: Traffic Evaluation on West 78th Street at the 9-ic- gc
Intersections of Laredo Drive and Market Boulevard ---
File No. PW070A-1
INTRODUCTION
1 Vehicles accessing or crossing West 78th Street via Laredo Drive
or Market Boulevard are presently experiencing significant delays
at various times during the day. As a part of a study to
determine solutions to remedy the problem, traffic counts have
recently been taken on West 78th Street at these two intersections .
The findings from the counts and recommendations for needed traffic
' control on West 78th Street are contained in the following report.
DATA COLLECTED AND OBSERVATIONS MADE
The intersection of West 78th Street and Laredo Drive is considered
a "T" intersection. However, this condition is modified somewhat
in that a primary access to the Chanhassen Mall area is located
directly across from Laredo Drive. This yields traffic movements
commonly associated with a "cross" intersection.
' Traffic counts were taken for the eastbound and westbound
directions of West 78th Street at locations just east and west of
Laredo Drive and on Laredo Drive just north of West 78th Street.
The traffic counts for this intersection were fairly substantial .
In fact, the volume recorded was actually large enough to warrant
a traffic control signal based on the "minimum vehicular volume"
criteria.
Traffic counts were also taken for the intersection of West 78th
Street and Market Boulevard. This intersection is a "cross"
intersection. Evaluating the counts on West 78th Street reveals
a continuously substantial traffic volume for almost all of the
daytime hours . However, the counts for Market Boulevard, the
minor street, were not high enough to specifically warrant a
traffic control signal at the present time.
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Gary Warren
September 5 , 1990
Page 2
Care must be taken in determining what type of traffic control
devices , if any, should be implemented on West 78th Street at
these intersections . It would be easy to reference a Minnesota
Manual of Uniform Traffic Control Devices warrant which calls for
signalization at Laredo Drive. However, this may or may not be
the appropriate long-term solution. Future road improvements to
T.H. 5 and T.H. 101 and the development of the vacant property
west of Market Boulevard will likely have a significant impact on
the future traffic and trip generations at these two
intersections . In fact, it is quite possible that a complete
traffic control plan coordinating the flow through all of the
intersections on West 78th Street from Powers Boulevard to T.H.
' 101 may be needed in the future. Nevertheless , it is the general
consensus that some sort of action should be taken at this time
to improve the situation at least in the interim.
Taking this into consideration, the multi-way stop alternative at
one or both of these intersections should be investigated.
Multi-way stop intersections are typically implemented where
traffic volumes on intersecting roads are nearly equal . However,
Section 2B-6 .1 of the Minnesota Manual of Uniform Traffic Control
Devices states that "where traffic signals are warranted and
' urgently needed, the multi-way stop is an interim measure that
can be installed quickly to control traffic while arrangements
are being made for the signal installation". This condition
based on total volume is satisfied only at the intersection with
' Laredo Drive.
Section 2B-6 . 2 recommends the installation of a multi-way stop at
' intersections where accidents are a problem as indicated by five
or more reported accidents in a 12-month period. Accident
reports for these two intersections were not readily available.
' However, experience has shown that as the duration of delay
increases for motorists , chances are that safe crossing and
access intervals will be challenged.
Section 2B-6 .3 further states that a multi-way stop sign
installation is also warranted based on minimum traffic volumes
if "the total vehicular volumes entering the intersection from
all approaches averages at least 500 vehicles per hour for any
eight hours of an average day, and the combined vehicular and
pedestrian volume from the minor street or highway averages at
least 200 units per hour for the same eight hours with an average
delay to minor street vehicular traffic of at least 30 seconds
per vehicle during the maximum hour . . . " . This condition is again
only satisfied currently at the intersection with Laredo Drive.
' No data has been acquired on the actual average delay to cars or
pedestrians from the minor street (Laredo Drive ) . However ,
personal experience at the intersection during the peak hour ,
4 :00 PM to 5:00 PM, has shown that the average delay may very
well exceed 30 seconds.
Gary Warren I
September 5, 1990
Page 3
CONCLUSION
It is apparent from data collected and observations made that '
some measures should be taken to control the traffic flow in the
vicinity of these two intersections. It was mentioned previously
that the traffic volume at Laredo Drive is high enough to warrant
signalization. However, it may be premature to incur the time
and expense ( $80-$100,000) until an evaluation can be made after
the proposed highway and commercial/retail improvements are
completed (Spring, 1992) .
The only other logical solution, at least for the interim, would
be the installation of a multi-way stop. The intersection at
Laredo Drive meets at least two of the three common warrants for
a multi-way stop. The intersection at Market Boulevard does not
meet any of the minimum requirements at this time; however, this
will likely change in the future pending ultimate
commercial/retail development in the area.
Subjectively reviewing the layout of West 78th Street in the '
vicinity of these two intersections with respect to driveway
access locations , site lines, etc. , it appears that the
intersection with Laredo Drive is the most appropriate location
for a multi-way stop installation. This multi-way stop would
also help to stagger cars westbound on West 78th Street and thus
allow for somewhat easier access at Market Boulevard.
In addition to approving a multi-way stop installation at the
Laredo Drive intersection, I would also recommend that "No
U-Turn" signs also be installed throughout West 78th Street.
Given the geometrics of the intersections and the fact that West
78th Street has a barrier median, the present u-turn movements
are hazardous and complicate traffic movements in the area.
RECOMMENDATION
Install a multi-way stop on West 78th Street at Laredo Drive as
an immediate interim solution to the traffic problems being
experienced, and install "No U-Turn" signs throughout West 78th
Street in the vicinity of the downtown businesses.
jms '
Attachment: Signage plan
c: Dave Hempel, Sr. Engineering Technician '
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CITY ENGINEER' S COMMENT
It may be appropriate at Council' s discretion to forward this
' item on to the Public Safety Committee for their review. The
impacts of the completion of T.H. 5 improvements to C.R. 17
( 1992 ) , the City' s West 78th Street detachment project ( 1991) ,
Market Square Retail (1991-92) and the T.H. 101 realignment
' ( 1991) all will have varying degrees of impact to the traffic
patterns in the downtown area.
' As such, I concur with the all-way stop conditions at Laredo and
West 78th Street as recommended by the Assistant City Engineer,
and the "No U-Turn" signs along West 78th Street. This matter
' will continue to be reevaluated by Engineering as construction
progresses and developments are computed.
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